U.S. patent number 4,579,982 [Application Number 06/594,385] was granted by the patent office on 1986-04-01 for preparation of monoalkylene glycols using two liquid phase reaction menstruum.
This patent grant is currently assigned to Union Carbide Corporation. Invention is credited to John R. Briggs, John H. Robson.
United States Patent |
4,579,982 |
Briggs , et al. |
April 1, 1986 |
Preparation of monoalkylene glycols using two liquid phase reaction
menstruum
Abstract
Alkylene oxides are hydrolyzed in a reaction menstruum
containing an aqueous phase, a water-immiscible liquid phase, and a
selectivity-enhancing, dissociatable metalate anion-containing
material. The concentration of the metalate anion-containing
material is greater in the water-immiscible liquid phase than that
in the aqueous phase. The water-immiscible liquid phase can be
separated from the aqueous phase to recover metalate
anion-containing material.
Inventors: |
Briggs; John R. (Charleston,
WV), Robson; John H. (Charleston, WV) |
Assignee: |
Union Carbide Corporation
(Danbury, CT)
|
Family
ID: |
24378656 |
Appl.
No.: |
06/594,385 |
Filed: |
March 28, 1984 |
Current U.S.
Class: |
568/867; 568/811;
568/833; 568/857 |
Current CPC
Class: |
C07C
29/106 (20130101); C07C 29/106 (20130101); C07C
31/205 (20130101); C07C 29/106 (20130101); C07C
33/26 (20130101); C07C 29/106 (20130101); C07C
31/202 (20130101); C07C 29/106 (20130101); C07C
31/207 (20130101); C07C 29/106 (20130101); C07C
35/14 (20130101); C07B 2200/09 (20130101); Y02P
20/52 (20151101); C07C 2601/14 (20170501) |
Current International
Class: |
C07C
29/00 (20060101); C07C 29/10 (20060101); C07C
031/20 (); C07C 033/26 (); C07C 035/14 (); C07C
033/035 () |
Field of
Search: |
;568/867,833,811,857 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
|
|
|
|
|
|
|
54-128507 |
|
Oct 1979 |
|
JP |
|
73035 |
|
Jun 1981 |
|
JP |
|
56-73036 |
|
Jun 1981 |
|
JP |
|
56-92228 |
|
Jul 1981 |
|
JP |
|
Other References
US.P.A. Ser. No. 530,235 filed 9/8/83. .
U.S.P.A. Ser. No. 594,264 filed 3/28/84. .
U.S.P.A. Ser. No. 594,268 filed 3/28/84..
|
Primary Examiner: Evans; J. E.
Attorney, Agent or Firm: Trinker; Steven T.
Claims
It is claimed:
1. A process for making alkylene glycols from alkylene oxide and
water comprising contacting the alkylene oxide with a
water-containing reaction menstruum under conditions sufficient to
form alkylene glycol, said water-containing reaction menstruum
comprising an aqueous phase; a water-immiscible liquid phase and a
selectivity-enhancing amount of a selectivity-enhancing,
dissociatable metalate anion-containing material comprising an
organometalate having an organic-containing cation, wherein said
water-immiscible liquid phase has a greater concentration of said
metalate anion-containing material than does the aqueous phase.
2. The process of claim 1 wherein the water-immiscible liquid phase
comprises a substantially water-insoluble organic solvent.
3. The process of claim 2 wherein the metalate anion-containing
material is substantially insoluble in water at 25.degree. C.
4. The process of claim 2 wherein the aqueous phase comprises the
continuous phase of the reaction menstruum.
5. The process of claim 2 wherein the water-immiscible liquid phase
comprises the continuous phase of the reaction menstruum.
6. The process of claim 2 wherein the metalate anion has the
formula [(A).sub.q M(O)].sup.a where M is a polyvalent metal having
a functional positive oxidation state; A represents one or more
substituents to fill the remaining valencies (q) of M, and a is the
negative charge of the anion.
7. The process of claim 6 wherein the metalate anion is selected
from the group consisting of vanadate, molybdate and tungstate.
8. The process of claim 6 wherein the alkylene oxide has the
formula ##STR3## wherein each of R.sup.1, R.sup.2, R.sup.3 and
R.sup.4 are the same or different and are hydrogen, alkyl of
between 1 and about 10 carbons, monocyclic or bicyclic aryl having
up to about 12 carbons, alkaryl having 7 to about 10 carbons,
monocyclic or bicyclic aralkyl having 7 to about 15 carbons,
alkenyl having 2 to 3 carbons, cycloalkyl having 3 to about 8
carbons, and cyclic structures joining two of R.sup.1, R.sup.2,
R.sup.3 and R.sup.4 having 3 to about 8 carbons.
9. The process of claim 8 wherein the alkylene oxide is ethylene
oxide.
10. The process of claim 2 wherein the mole ratio of metalate anion
to alkylene oxide is between about 0.1:100 to 1:1.
11. The process of claim 9 wherein the mole ratio of metalate anion
to ethylene oxide is between about 0.1:100 to 1:1.
12. The process of claim 6 wherein the organometalate is
preferentially soluble in the organic solvent as compared to water
at 25.degree. C.
13. The process of claim 12 wherein the organic-containing cation
is represented by the formula
wherein Y is a polyvalent element which is an ionic charge carrying
center; R.sup.0 is hydrogen or hydrocarbyl-containing substituent
with the proviso that Y has at least one R.sup.0 which contains a
hydrocarbyl substituent; m is the average number of electron pairs
shared by Y with the total R.sup.0 groups; and n is the number of
charge carrying centers, wherein m, n and x are related by the
equation x=n(V-m) in which V is the average functional oxidation
state of Y wherein each electron pair used by each Y in bonding to
R is given the value of 1 and the formal oxidation state of Y is
the sum of the electron pairs bonding to R.sup.0 and x/n, and x is
an integer of 1 or 2.
14. The process of claim 13 wherein the metalate anion is selected
from the group consisting of vanadate, molybdate and tungstate.
15. The process of claim 14 wherein the organic-containing cation
comprises an ammonium cation.
16. The process of claim 15 wherein the ammonium cation comprises a
tetraalkyl ammonium cation.
17. The process of claim 14 wherein the organic-containing cation
comprises phosphonium cation.
18. The process of claim 17 wherein the phosphonium cation
comprises a tetralkyl phosphonium cation.
19. The process of claim 14 wherein the organic-containing cation
comprises a bis(trisubstituted phosphine)iminium.
20. The process of claim 14 wherein the mole ratio of water to
alkylene oxide is from about 1:1 to 20:1.
21. The process of claim 20 wherein the mole ratio of water to
alkylene oxide is from about 1:1 to 10:1.
22. The process of claim 14 wherein the alkylene glycol is
preferentially soluble in the aqueous phase as compared to the
water-immiscible phase.
23. The process of claim 2 wherein the mole ratio of water to
alkylene oxide is from about 1:1 to 10:1.
24. The process of claim 23 wherein the water-immiscible phase and
the aqueous phase are separated after contact with alkylene oxide
and alkylene glycol is recovered from the aqueous phase.
25. The process of claim 24 wherein at least a portion of the
separated water-immiscible phase is subsequently contacted with
water and alkylene oxide.
26. A process for making alkylene glycols from alkylene oxide and
water comprising contacting the alkylene oxide with a
water-containing reaction menstruum under conditions sufficient to
form alkylene glycol, said water-containing reaction menstruum
comprising an aqueous phase; a water-immiscible liquid phase
comprising a substantially water-insoluble organic solvent which is
at least one member selected from the group consisting of benzene,
toluene, xylene, dichloromethane and 1,1,2-trichloroethane; and a
selectivity-enhancing amount of a selectivity-enhancing,
dissociatable metalate anion-containing material comprising an
organometalate having an organic-containing cation, wherein said
water-immiscible liquid phase has a greater concentration of said
metalate anion-containing material than does the aqueous phase.
Description
This invention relates to processes for the preparation of
monoalkylene glycols from alkylene oxides and water involving the
use of selectivity-enhancing, dissociatable metalate
anion-containing material. The processes of this invention enable
the production of monoalkylene glycols with high selectivity. In
the processes of this invention, a reaction menstruum containing an
aqueous phase and a water-immiscible liquid phase having a greater
concentration of the metalate anion than such concentration in the
aqueous phase is employed. Advantageously, the processes of this
invention facilitate the recovery of metalate anion from the
alkylene glycol product and water. This separation can, for
instance, be effected through phase separation and thereby enhance
the commercial viability of using metalate anion in the production
of monoalkylene glycol.
INTRODUCTION TO ALKYLENE GLYCOLS
Commercial processes for the preparation of alkylene glycols, for
example, ethylene glycol, propylene glycol and butylene glycol,
involve the liquid-phase hydration of the corresponding alkylene
oxide in the presence of a large molar excess of water (see, for
example, Kirk-Othmer, Encyclopedia of Chemical Technology, Vol. 11,
Third Edition, page 939 (1980)). The hydrolysis reaction is
typically conducted at moderate temperatures, e.g., about
100.degree. C. to about 200.degree. C., with water being provided
to the reaction zone in excess of 15 moles per mole of alkylene
oxide. The primary by-products of the hydrolysis reaction are di-
and polyglycols, e.g., dialkylene glycol, trialkylene glycol and
tetra-alkylene glycol. The formation of the di- and polyglycols is
believed to be primarily due to the reaction of alkylene oxide with
alkylene glycol. As alkylene oxides are generally more reactive
with alkylene glycols than they are with water, the large excesses
of water are employed in order to favor the reaction with water and
thereby obtain a commercially attractive selectivity to the
monoglycol product.
Since the alkylene glycols must be recovered from the hydrolysis
reaction mixtures, the large excess of water can result in an
energy intensive procedure. Typically, the water is removed by
evaporation to leave an alkylene glycol-containing residue which is
purified by distillation. Hence, a reduction in the amount of water
employed while maintaining, or enhancing, selectivity toward the
monoglycol product could be beneficial from the standpoint of
energy efficiency.
The hydrolysis reaction proceeds uncatalyzed; however, the presence
of acids or bases enhances the rate of reaction. Acid and base
catalysts, however, do have shortcomings. For instance, base
catalysts are generally not selective to the formation of the
monoglycol product and acid catalysts are typically associated with
corrosion problems. Hence, commercial processes typically utilize
relatively neutral hydrolysis conditions (for instance, pH
6-10).
Representative of the numerous acid catalysts that have been
suggested for use in the hydration of alkylene oxides include
fluorinated alkyl sulfonic acid ion exchange resins (U.S. Pat. No.
4,165,440, issued Aug. 21, 1979); carboxylic acids and halogen
acids (U.S. Pat. No. 4,112,054, issued Sept. 5, 1978); strong acid
cation exchange resins (U.S. Pat. No. 4,107,221, issued Aug. 15,
1978); aliphatic mono- and/or polycarboxylic acids (U.S. Pat. No.
3,933,923, issued Jan. 20, 1976); cationic exchange resins (U.S.
Pat. No. 3,062,889, issued Nov. 6, 1962); acidic zeolites (U.S.
Pat. No. 3,028,434, issued Apr. 3, 1962); sulfur dioxide (U.S. Pat.
No. 2,807,651, issued Sept. 24, 1957); trihalogen acetic acids
(U.S. Pat. No. 2,472,417, issued June 7, 1949); and copper-promoted
aluminum phosphate (U.S. Pat. No. 4,014,945, issued Mar. 29,
1977).
In addition to the acid catalysts, numerous catalysts have been
suggested for the hydration of alkylene oxides in the presence of
carbon dioxide. These include alkali metal halides, such as
chlorides, bromides and iodides; quaternary ammonium halides such
as tetramethyl ammonium iodide and tetramethyl ammonium bromide
(British Pat. No. 1,177,877); organic tertiary amines such as
triethylamine and pyridine (German published patent application No.
2,615,595, Oct. 14, 1976, and U.S. Pat. No. 4,307,256, issued Dec.
22, 1981); quaternary phosphonium salts (U.S. Pat. No. 4,160,116,
issued July 3, 1979); chlorine or iodine-type anion exchange resins
(Japanese Kokai No. 57/139,026, published Aug. 27, 1982); and
partially amine-neutralized sulfonic acid catalyst, e.g., partially
amine-neutralized sulfonic acid resin (U.S. Pat. No. 4,393,254,
issued July 12, 1983).
Various metal-containing compounds, including metal oxides, have
been proposed as catalysts for the hydrolysis of alkylene oxides.
For example, U.S. Pat. No. 2,141,443, issued Dec. 27, 1938,
discloses the production of glycols by the reaction of alkylene
oxide with water in the presence of a dehydrating metal oxide, for
example, alumina, thoria, or oxides of tungsten, titanium,
vanadium, molybdenum or zirconium. The reaction is carried out in
the liquid phase and under conditions of temperature and pressure
suited to maintain such phase. In example 7, the patentees disclose
rendering a yellow tungstic acid catalyst more mechanically stable
by admixture with a mixture of silicon ester, alcohol and water
followed by drying the catalyst. Similarly, U.S. Pat. No.
2,807,651, issued Sept. 24, 1957, states that it is known to
catalyze the reaction of an alkylene oxide and water by alkali
metal bases, alcoholates, oxides of titanium, tungsten and
thorium.
Many metals such as vanadium, molybdenum, tungsten, titanium,
chromium, zirconium, tantalum, rhenium, and niobium, have also been
proposed as components in catalysts for preparing 1,2-epoxides of
alpha-olefins and organic hydroperoxides. Often these catalysts are
present during a subsequent hydrolysis reaction. For instance,
Examples I and III or U.S. Pat. No. 3,475,499, issued Oct. 28,
1969, disclose that a mixture of normal alpha-olefins containing 11
to 15 carbon atoms was epoxidized with ethylbenzene hydroperoxide
in the presence of molybdenum naphthanate catalyst. After
distillation, the bottoms which contained the 1,2-epoxides and the
molybdenum-containing catalyst were contacted with water containing
0.5 percent sodium hydroxide at a temperature of 90.degree. C. That
reaction product was distilled and a conversion of 1,2-epoxides was
reported to be 100 percent and the selectivity to 1,2-glycols was
reported to be 94 percent.
More recently, U.S. Pat. No. 4,277,632, issued July 7, 1981,
discloses a process for the production of alkylene glycols by the
hydrolysis of alkylene oxides in the presence of a catalyst of at
least one member selected from the group consisting of molybdenum
and tungsten. The patent discloses that the catalyst may be
metallic molybdenum or metallic tungsten, or inorganic or organic
compounds thereof, such as oxides, acids, halides, phosphorous
compounds, polyacids, alkali metal and alkaline earth metal salts,
ammonium salts and heavy metal salts of acids and polyacids, and
organic acid salts. An objective of the disclosed process is stated
to be the hydrolysis of alkylene oxides wherein water is present in
about one to five times the stoichiometric value without forming
appreciable amounts of by-products such as the polyglycols. The
reaction may be carried out in the presence of carbon dioxide;
however, when the reaction is carried out in the presence of
nitrogen, air, etc., the patentees state that the pH of the
reaction mixture should be adjusted to a value in the range of 5 to
10. Japanese Kokai No. JA 54/128,507, published Oct. 5, 1979,
discloses a process for the production of alkylene glycols from
alkylene oxides and water using metallic tungsten and/or tungsten
compounds.
Japanese Kokai No. JA 56/073,035, published June 17, 1981,
discloses a process for the hydrolysis of alkylene oxide under a
carbon dioxide atmosphere in the presence of a catalyst consisting
of a compound containing at least one element selected from the
group of titanium, zirconium, vanadium, niobium, tantalum and
chromium. The compounds include the oxides, sulfides, acids,
halides, phosphorous compounds, polyacids, alkali metal salts of
acids and polyacids, ammonium salts of acids and polyacids, and
heavy metal salts of acids.
Japanese Kokai No. JA 56/073,036, published June 17, 1981,
discloses a process for the hydrolysis of alkylene oxide under a
carbon dioxide atmosphere in the presence of a catalyst consisting
of a compound containing at least one element selected from a group
comprising aluminum, silicon, germanium, tin, lead, iron, cobalt
and nickel.
Japanese Kokai No. JA 56/92228, published July 25, 1981, is
directed to processes for producing highly pure alkylene glycols.
The disclosure is directed to a distillation procedure for recovery
of a molybdenum and/or tungsten-containing catalyst from an
alkylene oxide hydrolysis process in the presence of carbon
dioxide. The application states that the catalyst is at least one
compound selected from the group consisting of compounds of
molybdenum and tungsten which compound may be in combination with
at least one additive selected from the group consisting of
compounds of alkali metals, compounds of alkaline earth metals,
quaternary ammonium salts and quaternary phosphonium salts. The
preferred catalysts are stated to be molybdic acid, sodium
molybdate, potassium molybdate, tungstic acid, sodium tungstate and
potassium tungstate. Potassium iodide is the only additive employed
in the examples.
U.S. patent applications Ser. Nos. 428,815, filed Sept. 30, 1982,
(now abandoned) and 530,235, filed Sept. 8, 1983, of J. H. Robson
and G. E. Keller, disclose the production of monoalkylene glycols
with high selectivity by the reaction of a vicinal alkylene oxide
with water in the presence of a water-soluble vanadate. Hence,
lower water to alkylene oxide ratios can be employed using the
disclosed process with attractive selectivities to the monoglycol
products. The counter ion to the vanadate is selected to provide a
water-soluble vanadate salt under the reaction conditions employed
and alkali metals, alkaline earth metals, quaternary ammonium,
ammonium, copper, zinc, and iron are suggested cations. It is also
disclosed that the vanadate may be introduced into the reaction
system in the salt form or on a support such as silica, alumina,
zeolites and clay. Since the vanadate ion is water soluble, it can
be lost from the reaction system and means must be provided to
recover it from the effluent from the reaction zone.
The processes specifically exemplified in, for instance, U.S. Pat.
No. 4,277,632 and Japanese Kokai Nos. JA 54/128,507, JA 56/073,035,
56/073,036, and 56/92228 employ a single phase reaction menstruum
in which the catalyst is apparently dissolved. In order to provide
monoalkylene glycol or merchantable quality, especially polyester
grade ethylene glycol, as well as to provide a commercially viable
process, the catalyst should be separated from the alkylene glycol
products in a form suitable to enable the catalyst to be recycled
to the process. Heretofore, fractional distillation procedures have
been suggested for the recovery of certain of these catalysts.
However, the stability of the catalysts during such distillation
has been noted as a particular problem. In Japanese Kokai Nos.
56/92228 and 56/118024 (published Sept. 16, 1981), the disclosures
state that during recovery of a molybdenum-containing catalyst by
distillation, a molybdenum hydrate can be formed which
precipitates, thereby increasing handling difficulties and
rendering the catalyst less active. Moreover, the pH of the
distillation column is made alkaline and ethylene glycol is
oxidized by the reduction of the molybdenum-containing catalyst,
both of which adversely affect the quality of the glycol product.
The disclosures specifically provide for the addition of water to
the still bottoms for the purpose of stabilizing the catalyst.
Recovering the catalyst by fractional distillation thus not only
provides the problem of energy consumption since the glycol
products must be separated as a vapor from the higher boiling
catalyst, but also the catalyst may be unstable and affect the
quality of the glycol products.
Copending U.S. patent application Ser. No. 594,268, filed on even
date herewith, of R. D. Best, J. A. Collier, B. T. Keen and J. H.
Robson, is directed to processes for the hydrolysis of alkylene
oxide in the presence of selectivity-enhancing metalate anion which
is in association with electropositive complexing sites on a solid
support. Readily available solids include anion exchange
resins.
OVERVIEW OF THE INVENTION
The processes of this invention relate to making alkylene glycols
by the hydrolysis of alkylene oxide with water using
selectivity-enhancing, dissociatable metalate anion-containing
material in a reaction menstruum containing two liquid phases. In
the reaction menstruum is provided an aqueous phase and a
water-immiscible liquid phase wherein the concentration of the
metalate anion-containing material in the water-immiscible phase is
greater than the concentration in the aqueous phase. Preferably,
essentially all of the metalate anion-containing material is
provided in the water-immiscible phase.
It has been found that even though the metalate anion-containing
material is in the non-aqueous phase, high selectivities to the
monoalkylene glycol can still be obtained. Advantageously, since
metalate anion-containing material is provided in the
water-immiscible phase, the recovery of the material from the
alkylene glycol product, which is soluble in the aqueous phase, is
facilitated and can readily be conducted under conditions that do
not unduly adversely affect the metalate anion or the quality of
the glycol product.
This invention thus provides processes for making alkylene glycols
with enhanced selectivities to the formation of monoalkylene
glycols wherein the recovery of the metalate anion-containing
material is facilitated without detriment to the activity of the
metalate anion or the quality of the glycol products. Moreover, the
processes may enable the use of metalate anions, such as the
vanadates, that are even more subject to instability than molybdate
or tungstate.
In aspects of this invention, the molar ratio of water to alkylene
oxide can be substantially reduced from those ratios employed in
conventional processes, thereby offering the potential of reduced
energy consumption in the recovery of the alkylene oxide from the
aqueous phase. Furthermore, despite the reduction in the amount of
water employed, undue temperatures in the reaction zone during the
exothermic hydrolysis need not be generated since the
water-immiscible phase provides additional heat capacity.
Accordingly, the processes of this invention offer considerable
design flexibility for integrated hydrolysis operations including
retrofit applications into existing, conventional alkylene glycol
manufacturing facilities.
DISCUSSION RELATING TO THE REACTANTS
Alkylene oxides which may be used to produce alkylene glycols in
the processes of this invention are vicinal alkylene oxides having
the general formula: ##STR1## wherein R.sup.1, R.sup.2, R.sup.3 and
R.sup.4 are the same or different and are hydrogen or
hydrocarbyl-containing substituents of 1 to about 20 carbon atoms.
Often R.sup.1, R.sup.2, R.sup.3 and R.sup.4 are hydrogen, alkyl of
between 1 and about 10 carbons, monocyclic or bicyclic aryl having
up to about 12 carbons, alkaryl having 7 to about 10 carbons,
monocyclic or bicyclic aralkyl having 7 to about 15 carbons,
alkenyl having 2 to 3 carbons, cycloalkyl having 3 to about 8
carbons, and cyclic structures joining two of R.sup.1, R.sup.2,
R.sup.3 and R.sup.4 having 3 to about 8 carbon atoms.
Representative of alkylene oxides are ethylene oxide, propylene
oxide, butylene oxide, including isobutylene oxide, 1,2-butylene
oxide and 2,3-butylene oxide, pentylene oxide, styrene oxide,
cyclohexene oxide and the like. Preferably, the alkylene oxide is
an aliphatic alkylene oxide having 2 or 3 carbon atoms, i.e.,
ethylene oxide and propylene oxide.
Alkylene oxides are well known, as is their preparation. For
example, alkylene oxide can be prepared by reacting an olefin with
an organohydroperoxide in the presence of a catalyst or by the
partial oxidation of an alkene with a molecular oxygen-containing
gas in the presence of a silver catalyst.
Water (as the liquid or steam) is also employed as a reagent for
the formation of the corresponding alkylene glycol. Usually the
water is of sufficient purity to provide a suitable quality
alkylene glycol product. Liquid water may be distilled or
demineralized, for example, by ion exchange treatment.
The metalate anions are characterized by an anionic structure
containing at least one metal atom and at least one oxygen ligand
that is conventionally characterized as a double-bonded oxygen
atom.
The metalate anions which may be useful in the processes of this
invention comprise a polyvalent metal having a positive functional
oxidation state, often an oxidation state of at least +3, say, +4
to +6 or +7, and may be a transition metal. The metalate anions may
be illustrated by the following formula:
wherein a- is the negative charge of the anion which is usually
between -1 and -4, A is one or more substituents to fill the
remaining valencies (q) of M and may be the same or different and
may be, for instance, double bonded oxygen; an organic radical such
as an alkyl, alkoxy, acyl, aryl, amino, phosphino, etc., usually of
1 to about 12 carbon atoms; halogen (e.g., chlorine, fluorine,
iodine); --O-- or --S-- wherein the remaining valency of the oxygen
atom is in free ionic form or is bonded to a metal atom (as in a
bimetal or polymetal-containing metalate) or cation. Most commonly
A is --O-- or .dbd.O. Even when the A in the starting
organometalate is other than --O--, e.g., chlorine, it is possible
that the original substituent becomes replaced by --O-- in the
course of the process.
Particularly preferred metals for the metalate anions include the
metals in groups Vb and VIb of the periodic chart such as vanadium,
molybdenum and tungsten, although other metals such as rhenium and
germanium may also find application. Representative metalate anions
which are especially useful include molybdate, tungstate,
metavanadate, hydrogen pyrovanadate and pyrovanadate (although
because of the complex chemistry associated with many metalate
anions, the precise structure of the operative specie or species
may be different). Frequently the metalate anion comprises at least
one anion conventionally characterized by the formulae [MoO.sub.4
].sup.2-, [VO.sub.3 ].sup.-, [V.sub.2 O.sub.7 H].sup.3-, [V.sub.2
O.sub.7 ].sup.4-, and [WO.sub.4 ].sup.2- ; however, it is
recognized that the chemistry of these metalate anions,
particularly the vanadates, is complex, and the exact chemical
formula under the conditions of the process may prove to be
different.
Not all metalate anions, including those of vanadium, tungsten and
molybdenum, exhibit desired activity with alkylene oxide. For
example, it has been observed that paramolybdate and paratungstate
anions (as the added metalate anion) appear to exhibit little, if
any, activity for enhancing selectivity.
Advantageously, the metal for the metalate anion is selected on the
basis of the nucleophilicity and electrophilicity in the anion with
respect to alkylene oxide in the environment. For example, the
metal as in the metalate often has a nucleophilicity with respect
to ethylene oxide greater than that exhibited by rhenium as in
rhenate anion under the same conditions. Also, it is frequently the
case that the metal as the metalate has an eletrophilicity with
respect to ethylene oxide greater than that exhibited by vanadium
as in orthovanadate (as that species) under the same
conditions.
A particularly convenient method for approximating nucleophilicity
and electrophilicity characteristics of a metal in a metalate anion
is by comparing the rate and selectivity to monoethylene glycol
under substantially the same hydrolysis conditions but employing an
equimolar amount (based on the anion) of the subject metalate anion
and the reference anion. For the sake of ease, the cation may be
sodium. If the rate and/or selectivity to the monoethylene glycol
is less than that provided by the rhenate anion, then the metal as
the metalate is probably less nucleophilic than rhenate with
respect to ethylene oxide. If the production of diethylene glycol
and polyethylene glycol is greater than that provided with
orthovanadate, regardless of the rate of formation of ethylene
glycols, then the metal as the metalate is probably less
electrophilic than orthovanadate with respect to ethylene
oxide.
The metalate anions are associated with a cation and are
dissociatable from the cation. Although the cations may be
substantially insoluble, or have little solubility, in water at
reaction conditions, the metalate anion can provide the enhanced
selectivity to monoalkylene glycol. However, if the metalate anion
is too tightly bound, it will not have the desired activity. Thus,
calcium vanadate, which has little solubility in water and retains
the metalate anion tightly bound, has not been found to be an
acceptable metalate-containing compound.
In accordance with one aspect of the invention, the cations render
the metalate-containing material preferentially soluble in an
organic medium as compared to water. Often, the metalate-containing
material will have a greater solubility in a given water-immiscible
organic solvent, such as toluene, than in distilled water at a
given temperature, say, 25.degree. C. In some instances, the
solubility coefficient is at least about 5 times, say, at least
about 20 times, greater in toluene than the solubility in distilled
water at 25.degree. C.
In another aspect of the invention, the metalate-containing
material is substantially insoluble in distilled water, e.g., less
than about 50, say, less than 10, grams of the metalate-containing
material will dissolve in one liter of water at 25.degree. C. Some
metalate-containing materials are immiscible with water and some
are solid at ambient temperatures, for instance, 25.degree. C., or
even at temperatures suitable for the processes of this invention,
e.g., about 50.degree. to 250.degree. C.
Particularly useful metalate-containing materials are those having
organic-containing cations (hereinafter referred to as
organometalates).
Organometalates may be represented by the formula:
wherein [(R.sup.0).sub.m Y.sub.n ].sup.x+ is an organic-containing
cation having a positive charge of x and Y is a polyvalent element,
which is an ionic charge carrying center, R.sup.0 is hydrogen or
hydrocarbyl-containing substituent with the proviso that the
organic-containing cation has at least one R.sup.0 which contains a
hydrocarbyl substituent, m is the average number of electron pairs
shared by Y with the total R.sup.0 groups, n is the number of
charge carrying centers, wherein m, n and x are related by the
equation x=n (V-m) in which V is the average functional oxidation
state of Y wherein each electron pair used by each Y in bonding to
R.sup.0 is given the value of 1 and the functional oxidation state
of Y is the sum of the electron pairs bonding to R.sup.0 and x/n,
wherein x is an integer of 1 or 2; wherein L is a cation which has
a positive charge of x' and which may be the same or different from
the organic-containing cation, where x' is usually 1 or 2; wherein
z is the number of organic-containing cations which is from 1 to 3.
Hence, the negative charge, a, of the metalate anion equals the
amount of x+[(z-1)(x')].
The hydrocarbyl-containing substituents useful in the
organic-containing cation frequently contain at least four carbon
atoms, and may be further substituted with moieties that are not
reactive with the anion.
L may be any suitable cation and often is another
organic-containing cation or a non-organic-containing cation which
serves to balance the charge of the anion. L may include alkali
metals, alkaline earth metals, copper, zinc, iron, ammonium
cations, phosphonium cations, sulfonium cations, and other cations
including organic-containing cations, e.g., containing alkyl,
alkoxy, acyl, aryl, amino, phosphino, etc., groups of 1 to about 12
carbons.
Suitable cations may include structures represented by the
formulae: ##STR2## where Y is nitrogen, phosphorous, or arsenic for
formula A, or sulfur for formula B, i.e., ammoniums, phosphoniums,
arsoniums and sulfoniums, where each of R.sup.5, R.sup.6, R.sup.7
and R.sup.8 may be the same or different and may combine to form
cyclic structures. Exemplary of each of R.sup.5, R.sup.6, R.sup.7
and R.sup.8 are hydrogen and unsubstituted and substituted
hydrocarbyls of 1 or more carbon atoms, e.g., to about 70 carbon
atoms. Representative cations are disclosed in copending U.S.
patent application Ser. No. 594,264, filed on on even date
herewith, of J. R. Briggs and J. H. Robson, herein incorporated by
reference.
Organic-containing cations which may be useful include the
bis(hydrocarbyl-phosphine) iminiums represented by the formula
wherein each R.sup.9 may be the same or different and may be the
same as set forth for R.sup.5 to R.sup.8. Illustrative iminiums are
disclosed in Ser. No. 594,264.
Illustrative of the organic-containing cations are tetrahydrocarbyl
ammoniums, e.g., tetramethyl ammonium, tetraethyl ammonium,
tetra-n-propyl ammonium, tetra-n-butyl ammonium, tetra-isobutyl
ammonium, trimethyl butyl ammonium, tetraheptyl ammonium,
tetraphenyl ammonium, tetrabenzyl ammonium, tetradodecyl ammonium,
tetraoctadecyl ammonium, and the like; trihydrocarbyl ammonium,
e.g., trimethyl ammonium, triethyl ammonium, triphenyl ammonium,
tridodecyl ammonium, trioctadecyl ammonium, and the like;
dihydrocarbyl ammoniums, e.g., dimethyl ammonium, diethyl ammonium,
di-n-butyl ammonium, di-n-heptyl ammonium, diphenyl ammonium,
dibenzyl ammonium, didodecyl ammonium, dioctadecyl ammonium, and
the like; hydrocarbyl ammoniums, e.g., methyl ammonium, n-butyl
ammonium, dodecyl ammonium, octadecyl ammonium, phenyl ammonium,
benzyl ammonium, and the like; tetrahydrocarbyl phosphoniums, e.g.,
tetramethyl phosphonium, tetraethyl phosphonium, tetra-n-propyl
phosphonium, tetra-n-butyl phosphonium, tetra-isobutyl phosphonium,
trimethyl butyl phosphonium, tetraheptyl phosphonium, tetraphenyl
phosphonium, tetrabenzyl phosphonium, tetradodecyl phosphonium,
tetraoctadecyl phosphonium, and the like; trihydrocarbyl
phosphonium, e.g., trimethyl phosphonium, triethyl phosphonium,
triphenyl phosphonium, tridodecyl phosphonium, trioctadecyl
phosphonium, and the like; dihydrocarbyl phosphoniums, e.g.,
dimethyl phosphonium, diethyl phosphonium, di-n-butyl phosphonium,
di-n-heptyl phosphonium, diphenyl phosphonium, dibenzyl
phosphonium, didodecyl phosphonium, dioctadecyl phosphonium, and
the like; hydrocarbyl phosphoniums, e.g., methyl phosphonium,
n-butyl phosphonium, dodecyl phosphonium, octadecyl phosphonium;
phenyl phosphonium, benzyl phosphonium, and the like;
bis(hydrocarbyl phosphine)iminiums such as
bis(triphenyl-phosphine)iminium, bis(tribenzyl-phosphine)iminium,
bis(trimethylphosphine)iminium, bis(tridodecyl-phosphine)iminium,
and the like; quaternized diamines such as
N,N'-bis(trimethyl)propylene diamine, N,N'-bis(triphenyl)propylene
diamine, N,N'-bis(trioctadecyl)propylene diamine; and quaternized
diphosphines such as P,P'-bis(trimethyl)propylene diphosphine, and
the like.
The metalate anion may be provided to the reaction mixture as a
metalate anion or in a form which is converted to the desired
metalate anion by subsequent chemical reaction. Hence, halide,
sulfide, or the like, metal-containing compounds may be employed as
the precursor to the desired metalate anion. Some of these
precursor compounds may be converted to metalates during the
hydrolysis reaction.
The metalate may be used in the salt form or may be introduced into
the reaction system on a support, such as on a carrier such as
silica, alumina, molecular sieves, zeolites, clay, and the like.
When the process is carried out, the metalate is generally in a
dissolved, mixed, suspended, or deposited form in a fixed bed in a
liquid phase. The metalate may be provided to the reaction system
by mixing it with alkylene oxide being introduced into the reaction
system, it may be introduced by means of a separate inlet to the
reaction system, or it may be retained in the reaction zone in an
immiscible organic phase. When the organometalate is water-soluble,
replenishing the reaction zone is desired. The exact means of
introduction of the metalate is not critical, and frequently the
metalate is provided at the beginning of the reaction and/or is
continuously or intermittently added at a fixed rate during the
reaction.
FORMATION OF ALKYLENE GLYCOLS
In the processes of this invention, alkylene oxide is contacted
with water in a water-containing reaction menstruum that comprises
an aqueous phase and a water-immiscible liquid phase.
The processes may be conducted in any suitable manner for reactions
in menstruum containing more than one phase. For instance, the
aqueous phase may provide the continuous phase or the
water-immiscible phase may be the continuous phase. In general, it
is desired that the discontinuous phase is highly dispersed and is
in the form of small bubbles to enhance the interface areas between
the phases. For example, the discontinuous phase can have bubble
diameters of less than about 2, say, less than about 1, e.g., about
0.01 to 0.5, centimeters. Devices to enhance the dispersion may be
employed such as agitators, spargers and the like. However, in
order to obtain an enhanced selectivity to monoalkylene glycol, it
is not usually essential to have a dispersed phase. Indeed, the
phases may form adjacent layers during conducting the reaction.
The relative amounts of the aqueous phase and the water-immiscible
liquid phase may vary widely, for instance, from 1000:1 to 1:1000
on a volume basis. Usually, the amount of the aqueous phase is
selected in respect to the amount of alkylene oxide employed in the
process since it is a reactant and must be separated from the
alkylene glycol products. Although in conventional alkylene oxide
hydrolysis processes the unreacted water serves as a heat sink to
assist in maintaining desired temperatures during the exothermic
hydrolysis reaction, in the processes of this invention such
considerations are often of less importance since the
water-immiscible phase provides some degree of heat sink capacity.
The mole ratio of water (which under the conditions of the process
may be provided in liquid form or steam) to alkylene oxide is often
in the range of about 0.5:1 to 50:1, and preferably, the amount of
water employed is at least sufficient on a stoichiometric basis to
react with all the alkylene oxide provided, e.g., the mole ratio is
at least 1:1 up to, say, about 40:1 or 50:1, say, about 1:1 to
20:1.
It is believed that the hydrolysis reaction in the processes of
this invention can proceed by at least two routes, one involving
the selectivity-enhancing metalate and the other being the
conventional route. Thus, the processes of this invention are
capable of producing dialkylene glycol and higher glycols. Hence,
the lower the ratio of water to alkylene glycol, all other factors
remaining the same, the greater the amount of these dialkylene and
higher glycols that will be produced. This provides a degree of
flexibility in operating processes of the invention to provide a
desired amount of these higher glycols but an amount less than
would be obtained in a conventional process. In most instances, the
mole ratio is in the range of about 3:1 to 10:1 (mole basis).
Another factor affecting the degree of selectivity to the
monoalkylene glycol is the amount of metalate anion employed.
Generally, the greater the amount of metalate anion employed, the
higher the selectivity to monoalkylene glycol, all other factors
remaining the same. Thus, the mole ratio of metalate anion to
alkylene oxide may be up to 5:1 or 10:1 or more. Economics usually
dictate that the mole ratio of metalate anion to alkylene oxide
will be less than about 2:1. Often, the mole ratio is at least
about 0.001:100, say, in the range of about 0.05:100 to 2:1, e.g.,
about 0.1:100 to 1:1, and most frequently about 1:100 to 0.5:1. For
purposes of determining the moles of metalate anion present, in
respect to anions containing more than one site which is available
for association with alkylene oxide, e.g., molybdate and tungstate,
the moles shall be calculated based on the number of such
sites.
The metalate anion-containing material may itself form the
water-immiscible phase, or it may be in combination with one or
more substantially water-insoluble components, e.g., solvents such
as water-immiscible organic liquids, in which the metalate
anion-containing material is dissolved. The solvent is preferably
non-reactive with alkylene oxide and the metalate anion-containing
material. However, in some instances it may be desirable to use
interactive solvents such as 1,2-dimethoxyethane in addition to the
substantially water-insoluble solvent. The preferred solvents are
those in which the metalate anion-containing material is
preferentially soluble in comparison to water under the conditions
of the hydrolysis reaction. Frequently, the metalate
anion-containing material is at least about 5 times more soluble in
the solvent than in water at 25.degree. C. This characteristic of
the solvent facilitates the recovery of the metalate
anion-containing material from the glycol-containing aqueous phase.
Often the metalate anion-containing material is highly soluble in
the solvent. Usually, at 25.degree. C., it is soluble in the
solvent in an amount of at least about 50 grams per liter.
Exemplary of liquid solvents are alkyl, cycloalkyl and
aromatic-containing solvents, especially halogenated alkyl,
cycloalkyls and aromatics, such as cyclopentane, cyclohexane,
methylcyclohexane, cycloheptane, benzene, toluene, xylene,
naphthene, dichloromethane, 1,1,2-trichloroethane and the like.
Also, silicone oils and mineral oils may be useful. Not all the
above solvents will be suitable for all of the processes of this
invention.
The water-immiscible liquid phase may be denser or less dense than
water. Often, the density of the water-immiscible liquid phase is
sufficiently different than that of the aqueous phase to facilitate
phase separation, e.g., the densities may differ by at least about
0.05, say, at least about 0.1, gram per cubic centimeter under the
conditions of the hydrolysis reaction.
The amount of solvent, when employed, can vary widely and is
frequently in the range of about 0.1:1 to 10:1 volumes per volume
of water. The amount of solvent employed is often determined based
upon the solubility of the metalate anion-containing material in
the solvent, whether the water-immiscible phase is to be the
continuous phase, the desired mass for the dissipation of heat from
the exothermic hydrolysis reaction, and the like.
The hydrolysis can be conducted under conditions sufficient to
maintain the aqueous phase and the water-immiscible phase as
liquids and to effect the hydrolysis. The temperature, however,
should not be so great that the metalate anion-containing material
is unduly adversely affected. Frequently, the reaction temperature
is between about 20.degree. C. and about 220.degree. C. or
250.degree. C., say, between about 50.degree. C. and 200.degree.
C., and sometimes between about 80.degree. C. and 180.degree.
C.
The processes may be conducted at subatmospheric, atmospheric or
superatmospheric pressure. For purposes of convenience, the
reaction is typically conducted at pressures greater than ambient,
e.g., between about 0.1 and 1000 kilograms per square centimeter
gauge, and preferably between about 2 and 100 kilograms per square
centimeter gauge.
The hydrolysis may be conducted for a time insufficient for
complete reaction, but it is generally preferred that when water is
provided in amounts sufficient for complete reaction with the
alkylene oxide, the reaction is conducted for a period of time
sufficient to ensure that substantially all the alkylene oxide is
reacted. The amount of time required to accomplish the
substantially complete reaction is determined by the other
conditions employed including temperature, amount of reactants
present, and the like. The reaction may be carried out for very
short periods of time; e.g., fractions of a second, and, if
desired, may be carried out for periods of up to hours, e.g. about
0.01 second to 5 hours, preferably about 1 second to 30
minutes.
The alkylene oxide may be a gas under the conditions of the
reaction and may be introduced into the liquid medium as a fine
dispersion of gas bubbles, but, most frequently, the pressure is
sufficient to maintain the alkylene oxide in the liquid phase.
The hydrolysis may be conducted in the presence of a gas, which is
preferably inert. Gases which may be employed include air, carbon
dioxide, nitrogen, argon and the like. Carbon dioxide is often
present by the very nature of the process and the source of the
alkylene oxide (especially by partial oxidation of alkenes).
Frequently, it is desired to maintain the mole ratio of carbon
dioxide to alkylene oxide less than 0.1:1, particularly less than
0.05:1, unless it is desired to affect the pH of the reaction
menstruum.
The pH of the reaction menstruum is frequently maintained
relatively neutral, e.g., between about 5 and 11, preferably about
6 to 10.5, and most often the pH is in the range of about 6 to 10.
With some metalate anions, such as the vanadates, tungstates and
molybdates, the pH of the medium can be determinative of the
species present. For example, in strong bases the orthovanadate may
predominate, but at neutral conditions metavanadate may
predominate. In another example, more acidic media promote the
formation of polynuclear molybdates which often have less, if any,
activity towards forming the associated moiety.
The pH may be maintained within the desired range by the addition
of acid or base, or the addition of buffers, as is well known in
the art. However, the presence and nature of salts should be
considered since the cation may displace the cation for the
metalate anion. Mechanisms which have been proposed for maintaining
the desired pH in other types of hydrolysis processes include the
addition of carbon dioxide or inorganic acids or organic acids such
as sulfuric acid, hydrochloric acid and acetic acid. The agents for
maintaining the pH value of the reaction menstruum may be added in
any convenient manner such as during the reaction, e.g., by purging
with carbon dioxide, or by addition to one or more of the reactants
prior to introducing the reactants into the reactor.
The maintenance of the pH within the desired ranges can also have a
secondary effect of enhancing the stability of the metalate
anion.
The stability of organometalates when used in processes in
accordance with this invention may be enhanced by the addition of
small quantities of metalate anion-containing material to the
water-immiscible phase. The added metalate anion is often provided
in amounts less than 1000 ppm by weight with a mole ratio of added
metalate anion to organometalate of about 1:50 to 1:1000. The added
metalate anion-containing material can conveniently be provided as
a more water-soluble salt, e.g., sodium or potassium metalate. See
U.S. patent application Ser. No. 594,267, filed on event date
herewith, of B. T. Keen, herein incorporated by reference, for
further discussion.
The processes of this invention may be conducted batch-wise,
semi-continuously or continuously using suitable processing
equipment. For example, the reaction may be conducted in a vessel
provided with means to promote the contact between the phases,
e.g., agitators, packing, trays, spargers, or the like. The feed,
or various components, may be premixed before being introduced into
the reactor or the components may be separately introduced into the
reaction vessel. For instance, a water-immiscible liquid phase can
be admixed with alkylene oxide and introduced into an aqueous phase
in the reaction vessel. Alternatively, alkylene oxide may be
separately introduced into a reaction vessel containing a
water-immiscible liquid phase and an aqueous phase. In any event,
the process should be operated such that at least a portion of the
alkylene oxide has an opportunity to contact the substantially
water-insoluble phase containing the metalate anion-containing
material prior to reaction with water.
It is usually desired to separate the alkylene glycol product from
the reaction menstruum and to recover the metalate anion-containing
material for further use in the process. Since the alkylene glycol
is usually preferentially soluble in a liquid, aqueous phase, the
glycol products can be removed by phase separation (e.g.,
decanting, centrifugation) from the water-immiscible phase and then
recovered. The alkylene glycol-rich aqueous phase can be refined to
recover high purity monoalkylene glycol, for instance, by the use
of multiple effect evaporators to remove water and distillation,
e.g., vacuum distillation, to refine the monoalkylene glycol from
higher glycol impurities and other impurities. The metalate
anion-containing material within the separated, water-immiscible
phase can be recycled for further use.
In some instances, the separated aqueous phase may contain some
dissolved metalate anion-containing material after the phase
separation. If desired, this metalate anion-containing material may
be recovered by suitable techniques. For example, the metalate
anion-containing material can be extracted from the aqueous phase
by contact with an immiscible liquid in which the metalate anion or
its associated cation is preferentially soluble. For further
discussion see U.S. patent application Ser. No. 594,266, filed on
even date herewith, of B. T. Keen, et al., herein incorporated by
reference. Alternatively, the aqueous phase may be contacted with,
for instance, an anion exchange resin such as a chloride-loaded
DOWEX (TM) MSA-1 resin available from the Dow Chemical Company to
recover the metalate anion. This resin can be separated and
regenerated with the recovery of the metalate anion. See, for
further discussion, U.S. patent application Ser. No. 594,269, filed
on even date herewith, of J. A. Collier, herein incorporated by
reference. It is also possible to recover the metalate
anion-containing material by distillation (e.g., evaporation or
fractional distillation) from the alkylene glycols. When employing
higher temperature separation processes, e.g., above about
100.degree. or 120.degree. C., the provision of small amounts of
water enhances the stability of many metalate anions.
The following examples are provided to assist in the understanding
of the invention and are not in limitation thereof. All percentages
and parts of solids are by weight and all percentages and parts of
liquids and gases are by volume unless otherwise indicated.
The analyses of the reaction products were conducted by temperature
programmed gas chromatography. One method used a 10 ft.times.1/8"
stainless steel column packed with Chromosorb 101 (TM) (60/80
mesh). Sample injections (2-3 microliters) were made from a sample
of 1.5 to 2.0 grams of hydrolysis product to which had been added
0.12 to 0.15 gram of 2-ethyl-1,3-hexanediol as internal
standard.
In another method, the samples are prepared by adding about 2
weight percent 1,3-butanediol as an internal standard.
Approximately 50 microliters of this admixture are added to 1.0
milliliter of Regisil (TM) (BSTFA) (N,N-bis trimethylsilyl
trifluoroacetamide), available from the Regis Chemical Company,
Morton Grove, Ill., in a serum vial and mixed for at least about 12
hours. The weight percent monothylene glycol, diethylene glycol and
triethylene glycol are determined by standard vapor phase
chromatography using a Hewlett Packard 5880 (TM) gas chromatograph
equipped with a four meter by 1/8 inch (0.32 centimeters) (outside
diameter) stainless steel column packed with 20 percent OV-101
methylsilicone stationary liquid phase supported on 80/100 mesh
Chromosorb W HP (TM) both available from Supelco, Inc. Bellefonte,
Pa.
Selectivities are defined as [G/(M+D+T)] times 100% where G is the
weight of the glycol in question, M is the weight of monoalkylene
glycol, D is the weight of dialkylene glycol and T is the weight of
trialkylene glycol.
Unless otherwise stated, the examples were conducted using a 300
milliliter Parr reactor.
EXAMPLE 1
The reactor was charged with 16.04 grams of ethylene oxide, 16.19
grams of distilled water, 2.92 grams of bis[tetra-n-hexyl)ammonium]
molybdate and 26.24 grams of toluene. A two-phase reaction medium
resulted and the mixture was continuously stirred to maintain a
dispersion of the phases. The reaction medium was heated to about
140.degree. C. for slightly over one hour. During the reaction, the
pressure increased to about 160 psig and then fell to about 40
psig. The reactor was cooled with cooling water and then ice water
to about 5.degree. C. and opened. The aqueous layer was recovered
and analyzed to contain monoethylene glycol (89% selectivity),
diethylene glycol (11% selectivity), and triethylene glycol (less
than 1% selectivity).
EXAMPLE 2
The reactor was charged with 15.4 grams of ethylene oxide, 15.4
grams of distilled water, 0.775 grams of
bis[tetra-n-heptyl)ammonium] tungstate and 27.67 grams of toluene.
A two-phase reaction medium resulted and the mixture was
continuously stirred to maintain a dispersion of the phases. The
reaction mixture was heated to about 140.degree. C. for about 3
hours. During the reaction the pressure increased to about 155 psig
and dropped to about 50 psig. The reactor was then cooled with
cooling water and then ice water to about 2.degree. C. The aqueous
layer was recovered and analyzed to contain monoethylene glycol
(68% selectivity), diethylene glycol (26% selectivity) and
triethylene glycol (6% selectivity).
EXAMPLE 3
A 50 milliliter, round bottom, glass flask was charged with 10.0
grams of bis(triphenylphosphine)iminium vanadate and 10 milliliters
of dichloromethane. The solution was cooled to below 10.degree. C.,
and 6.91 grams of ethylene oxide (about 0.degree. C.) were then
added. After weighing the flask, 6.91 grams of distilled water
(about 0.degree. C.) were added to form a two-phase reaction
mixture. The mixture was stirred rapidly and refluxed (about
35.degree. C.) under a dry ice/acetone condenser for about 7 hours.
The mixture was then allowed to stand at ambient temperature
overnight. The aqueous layer was then removed from the organic
layer and analyzed to contain monoethylene glycol. No diethylene or
triethylene glycol was detected.
EXAMPLE 4
A stirred, 50 milliliter, round bottom, glass flask, equipped with
a condenser was charged with 1.0 grams of
bis[bis(triphenylphosphine)iminium] molybdate, 5 milliliters of
cyclohexene oxide, 1.0 milliliter of distilled water and 5.0
milliliters of 1,1,2-trichloroethane. The mixture was heated to
reflux (at ambient pressure) while cooling the condenser with dry
ice/acetone for three hours. The heating and stirring was stopped
and reinitiated about 15 to 16 hours later and continued for about
7.5 hours. A brown-colored solution was produced. Water and
cyclohexane oxide were removed from the mixture under vacuum (about
1 to 2 L millibars absolute) at about 35.degree. C. to 40.degree.
C. A white solid condensed on the side of the flask. The solid had
a melting point of about 100.5.degree. C. to 101.5.degree. C.
Analysis by infrared spectroscopy indicated that the product was
exclusively 1,2-trans-dihydroxycyclohexane.
EXAMPLES 5 TO 9
In these examples, the following general procedure was used. Into
the reactor were introduced a previously prepared solution of the
organometalate in solvent using vacuum to assist in the transfer.
The water was then charged and the autoclave purged with nitrogen
and vented. Cooled ethylene oxide (liquid) was injected into the
autoclave under nitrogen pressure. The reaction menstruum was
stirred at a stirrer rotation rate of about 800 rpm. The autoclave
was pressurized to about 3.5 atmospheres absolute, heated and then
maintained at substantially a constant temperature for about one
hour. The pressure was allowed to rise. After cooling, a portion of
the aqueous phase was withdrawn for analysis. The details of the
examples are provided in Table I.
TABLE I
__________________________________________________________________________
Metalate Anion- Containing Material Ethylene Selectivity Example
Identity Amount, g Water, g CH.sub.2 Cl.sub.2, g Oxide, g Temp.
.degree.C. to MEG, %
__________________________________________________________________________
5 (PPN) VO.sub.3 * 8.3 33.0 33.0 33.0 140.degree. C. 73.7% 6
(PPN).sub.2 MoO.sub.4 ** 8.3 33.0 33.0 34.0 140.degree. C. 86.7% 7
(control) -- -- 33.0 33.0 33.0 140.degree. C. 58.7% 8 (control)
Na.sub.2 MoO.sub.4 *** 1.38 33.0 33.0 34.0 140.degree. C. 87.4% 9
(PPN).sub.2 MoO.sub.4 7.9 33.0 33.0 33.0 100.degree. C.**** 83.4%
__________________________________________________________________________
*bis(triphenylphosphine)iminium
**bis[bis(triphenylphosphine)iminium]molybdate ***preferentially
soluble in water ****reactor temperature maintained for about two
hours
EXAMPLES 10 TO 13
In these examples the following general procedure was used. A stock
solution of ethylene oxide (33 grams) and water (71 grams) was
prepared in syrum bottle and maintained at about 2.degree. C. A
separate stock solution of toluene (10 grams) and
bis(tetrahexylammonium)molybdate (BTHAM) (4.5 grams) was prepared
in 120 cubic centimeter syrum bottles at room temperature (about
22.degree. C.). Aliquots of each stock solution were introduced
into chilled (about 2.degree. C.) stainless steel tubular
microreactors (exterior dimensions of about 9.6 millimeters by 76
millimeters) that are capable of being immersed in a constant
temperature bath. The microreactors were purged with nitrogen prior
to the introduction of the materials. After introducing the
materials, the reactors were sealed and immersed in the bath while
under a reciprocating motion to promote agitation. After about one
hour, the microreactors were withdrawn from the bath and cooled to
about 0.degree. C. in an ice bath. Samples of the aqueous phase
were withdrawn and analyzed. The details of the examples are
provided in Table II.
TABLE II ______________________________________ Selec- Ex- tivity
am- Water, Toluene, Ethylene BTHAM, Temp., to MEG, ple g g Oxide, g
g .degree.C. % ______________________________________ 10 0.38 1.42
0.17 0.64 110.degree. C. 97.3 11 1.47 0.36 0.69 0.16 110.degree. C.
91.5 12 0.38 1.42 0.17 0.64 140.degree. C. 98.5 13 1.47 0.36 0.69
0.16 140.degree. C. 91.2 ______________________________________
EXAMPLE 14
Into an evacuated (about 10 millibar absolute) glass vessel at room
temperature, containing one gram of bis(triphenylphosphine)iminium
metavanadate, was introduced a mixture of 50 weight percent
ethylene oxide and 50 weight percent argon until the pressure in
the vessel had increased by about 500 to 550 millibars. Then a
mixture of 10 milliliters of water and 50 milliliters of
1,1,2-trichloroethane was syringed into the reactor. The reactor
was heated to reflux while stirring magnetically. After about one
hour a circulating pump was turned on. The system was shut down
after about 3 hours and allowed to sit overnight. Then an
additional 4 milliliters of ethylene oxide were added and the
system restarted. After about 2 hours, the solvent layer was
distilled under vacuum and heat with several washings of
1,1,2-trichloroethane (72.3 grams of solvent layer recovered). An
aqueous layer of 41.4 grams was obtained and a sample was analyzed
to contain monoethylene glycol.
EXAMPLE 15
Under an argon atmosphere 5.28 grams of tetrahexylammonium
molybdate were added to a 100 milliliter glass flask. The flask was
then cooled to about 10.degree. C. and 9.66 grams of ethylene oxide
were poured into the flask and then about 9.61 grams of distilled
water (about 0.degree. C.) were added. The flask was purged with
argon and then refluxed using dry ice in an acetone cooled
condenser for 5 hours then the condenser was allowed to warm to
room temperature. The apparatus was allowed to stand overnight.
About 9 milliliters of water were added with shaking and then about
30 milliliters of toluene were added and three distinct phases
formed. The aqueous layer was found to contain monoethylene
glycol.
EXAMPLES 16 TO 25
Substantially the same procedure described in Examples 1 and 2 was
employed in these examples. The details are provided in Table III.
In all examples except 18 and 19, the stirring was at about 420
rpm. In example 18, the stirrer rate was about 840 rpm and in
example 19, 300 rpm. In all but example 20, the maximum temperature
of the reaction menstruum was about 140.degree. C. In example 20,
it was about 170.degree. C.
TABLE III ______________________________________ Metalate-Anion
Containing Selec- Ex- Material Solvent tivity am- Ethylene Wa-
Iden- Amount, Iden- A- to MEG, ple Oxide, g ter tity g tity mount %
______________________________________ 16 16.0 16.2 A 0.81 T 30 ml
76.2% 17* 16.0 16.1 A 0.80 T 30 ml 79.4% 18 16.3 16.2 A 0.81 T 30
ml 74.6% 19 16.3 16.4 A 0.81 T 30 ml 75.7% 20 16.4 16.6 A 0.82 T 30
ml 78.9% 21 16.0 15.5 A 4.90 T 30 ml 93.7% 22** 16.2 16.3 C 1.0 H
30 g 61.8% 23 15.6 15.5 B 1.5 H 30 g 64.8% 24 15.8 15.2 B 1.5 E 30
g 64.2% 25 14.9 15.1 A 1.5 M 45 g 87.5%
______________________________________ *Heating for 1/2 hour,
insufficient time for complete reaction of ethylen oxide. **Organic
phase contains catalyst
Metalate Anion-Containing Materials Solvent A Bis(tetra-n-hexyl- H
Hexane Ammonium)molybdate B Bis(tetra-n-octadecyl- E Dibutyl ether
Ammonium)molybdate C Bis(tetra-n-dodecyl- M 20g toluene and 25g
Ammonium)molybdate triphenylphosphine oxide T Toluene
EXAMPLE 26
Substantially the same procedure described in Example 1 was
employed except that the toluene-containing layer was recovered
from a reaction medium and was used in a subsequent reaction
medium. The aqueous layer from the reaction yielding the toluene
was extracted twice with about 10 milliliters of toluene and a
portion of the rinse toluene was also used in the subsequent
reaction.
The first run employed about 1.5 grams of
bis(tetra-n-hexylammonium)molybdate. The details are provided in
Table IV.
The low selectivities in runs 2 to 5 are believed to be due to
difficulty in obtaining a good and rapid phase separation. A more
preferable solvent would be, e.g., dichloromethane.
TABLE IV ______________________________________ Ethylene Water,
Recycle Rinse Selectivity Run Oxide, g g Toluene, g Toluene, g to
MEG, % ______________________________________ 1 16.0 15.4 (Fresh
Toluene, 30 g) 82.3% 2 15.8 15.5 27.8 3.6 43.2% 3 15.6 15.3 28.6
2.9 32.2% 4 15.8 15.4 26.4 5.1 44.2% 5 15.5 15.5 30.0 1.8 47.0%
______________________________________
Table V, which follows, provides a further expansion of the
principles illustrated in the preceding examples.
TABLE V
__________________________________________________________________________
Example Metalate Anion- Mole Ratio/ No. Containing Material
Alkylene Oxide Metalate:Oxide Solvent Predominant
__________________________________________________________________________
Product 27 tetra-n-hexylammonium ethylene oxide 1:5 dichloromethane
monoethylene glycol vanadate (pH 10) 28 tetra-n-hexylammonium
ethylene oxide 1:1 toluene monoethylene glycol (Comparison) rhenate
(no enhanced selectivity) 29 bis[bis(triphenyl- propylene oxide
0.005:1 dichloromethane propylene glycol phosphonium)iminium]
molybdate 30 bis[bis(triphenyl- styrene oxide 0.01:1
dichloromethane 1,2-dihydroxyethylbenzene phosphonium)iminium]
molybdate 31 bis[bis(triphenyl- 1,2 epoxybutane 0.006:1
dichloromethane 1,2-butanediol phosphonium)iminium] molybdate
__________________________________________________________________________
EXAMPLE 32 (Comparative)
The reactor was charged with 15.19 grams of distilled water, 30
milliliters of toluene and (after cooling to about
0.degree.-5.degree. C.) 14.97 grams of ethylene oxide. The mixture
was stirred and heated to about 140.degree. C. for about 3.5 hours,
cooled to about 2.degree. C. in ice water. The aqueous layer was
recovered and analyzed to contain monoethylene glycol (56%
selectivity), diethylene glycol (33% selectivity) and triethylene
glycol (11% selectivity).
* * * * *